//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.server;

import org.eclipse.jetty.io.AbstractConnection;
import org.eclipse.jetty.io.Connection;
import org.eclipse.jetty.io.EndPoint;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.net.ssl.SSLEngine;
import javax.net.ssl.SSLEngineResult;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;

public abstract class NegotiatingServerConnection extends AbstractConnection {
    private static final Logger LOG = LoggerFactory.getLogger(NegotiatingServerConnection.class);
    private static final ByteBuffer EMPTY_WRITABLE_BUFFER = ByteBuffer.allocate(0);
    private final Connector connector;
    private final SSLEngine engine;
    private final List<String> protocols;
    private final String defaultProtocol;
    private String protocol; // No need to be volatile: it is modified and read by the same thread
    protected NegotiatingServerConnection(Connector connector, EndPoint endPoint, SSLEngine engine, List<String> protocols, String defaultProtocol) {
        super(endPoint, connector.getExecutor());
        this.connector = connector;
        this.protocols = protocols;
        this.defaultProtocol = defaultProtocol;
        this.engine = engine;
    }

    public List<String> getProtocols() {
        return protocols;
    }

    public String getDefaultProtocol() {
        return defaultProtocol;
    }

    public Connector getConnector() {
        return connector;
    }

    public SSLEngine getSSLEngine() {
        return engine;
    }

    public String getProtocol() {
        return protocol;
    }

    protected void setProtocol(String protocol) {
        this.protocol = protocol;
    }

    @Override
    public void onOpen() {
        super.onOpen();
        fillInterested();
    }

    @Override
    public void onFillable() {
        int filled = fill();

        if (filled == 0) {
            if (protocol == null) {
                if (engine.getHandshakeStatus() == SSLEngineResult.HandshakeStatus.NOT_HANDSHAKING) {
                    // Here the SSL handshake is finished, but the protocol has not been negotiated.
                    if (LOG.isDebugEnabled())
                        LOG.debug("{} could not negotiate protocol, SSLEngine: {}", this, engine);
                    close();
                } else {
                    // Here the SSL handshake is not finished yet but we filled 0 bytes,
                    // so we need to read more.
                    fillInterested();
                }
            } else {
                ConnectionFactory connectionFactory = connector.getConnectionFactory(protocol);
                if (connectionFactory == null) {
                    LOG.info("{} application selected protocol '{}', but no correspondent {} has been configured",
                            this, protocol, ConnectionFactory.class.getName());
                    close();
                } else {
                    EndPoint endPoint = getEndPoint();
                    Connection newConnection = connectionFactory.newConnection(connector, endPoint);
                    endPoint.upgrade(newConnection);
                }
            }
        } else if (filled < 0) {
            // Something went bad, we need to close.
            if (LOG.isDebugEnabled())
                LOG.debug("{} detected close on client side", this);
            close();
        } else {
            // Must never happen, since we fill using an empty buffer
            throw new IllegalStateException();
        }
    }

    private int fill() {
        try {
            return getEndPoint().fill(EMPTY_WRITABLE_BUFFER);
        } catch (IOException x) {
            LOG.debug("Unable to fill from endpoint {}", getEndPoint(), x);
            close();
            return -1;
        }
    }

    @Override
    public void close() {
        // Gentler close for SSL.
        getEndPoint().shutdownOutput();
        super.close();
    }

    public interface CipherDiscriminator {
        boolean isAcceptable(String protocol, String tlsProtocol, String tlsCipher);
    }
}
